Soros Fund Management bought $35 million worth of Tesla bonds in the first quarter of 2018.: George Soros' investment firm bought a large amount of Tesla bonds in the first quarter of 2018, giving the under pressure electric carmaker a major backer, a regulatory filing shows. Soros Fund Management bought $35 million worth of convertible notes, which are bonds that can be converted into a specified number of common stock, according to a Securities and Exchange Commission (SEC) filing released on Tuesday. The convertible bond is due in March 2019. Tesla has had a tough start to the year.